There are 2 major and 2 minor studies being conducted. The Major Studies are: 1. A Double-blind Crossover of Methylphenidate in the Treatment of Adults with Persumptive Minimal Brain Dysfunction; 2. A Study of CSF and Urinary Monoamine Metabolites in Adults with Persumptive MBD. The Minor Studies are: 1. A Determination of Frequency of Adult MBD in an Alcoholic Population; 2. Preliminary Analysis of Proposed Adult MBD Questionnaires & Their Utilization in Psychiatrically Disturbed Populations; 3. A possible Trial of L-Dopa as a Supplement to Methylphenidate in the Treatment of Adult MBD.